 /*******************************************************************************
  * Copyright (c) 2000, 2003 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Common Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal;

  
 import org.eclipse.ui.*;

 /**
  * A perspective service tracks the activation and reset of perspectives within a
  * workbench page.
  * <p>
  * This interface is not intended to be implemented by clients.
  * </p>
  *
  * @see IWorkbenchPage
  */
 public interface IPerspectiveService {
 /**
  * Adds the given listener for a page's perspective lifecycle events.
  * Has no effect if an identical listener is already registered.
  *
  * @param listener a perspective listener
  */
 public void addPerspectiveListener(IInternalPerspectiveListener listener);
 /*
  * Returns the active perspective descriptor in the active workbench page.
  *
  * @return the active perspective descriptor, or <code>null</code> if no perspective is currently active
  */
 public IPerspectiveDescriptor getActivePerspective();
 /**
  * Removes the given page's perspective listener.
  * Has no affect if an identical listener is not registered.
  *
  * @param listener a perspective listener
  */
 public void removePerspectiveListener(IInternalPerspectiveListener listener);
 }

